Known in the prior art is a roller-vane hydraulic machine (SU, A, 567844) comprising a hollow casing with working fluid inlet and outlet passages.
The casing accommodates a rotor with vanes and slotted rollers. The rotor and rollers rotate in synchronism under the effect of the supplied energy. The casing and rotor surfaces form a working chamber divided by rollers into larger and smaller inter-roller chambers. The surfaces of the rollers form sealing clearances together with the surfaces of the casing and rotor. The smaller inter-roller chambers intercommunicate through hydraulic relief passages in the casing. The hydraulic relief of the rotor in the hydraulic machine is incomplete due to the following reason. In the course of rotor rotation there comes a moment when the larger inter-roller chambers get closed. Then the pressure difference in these chambers may reach considerable values.
This brings about a unilateral pressing of the rotor against the casing and a change in the sealing clearances. This leads to increased internal leaks on the working stroke and increased pressure losses on the idle stroke.
The mechanical and volumetric efficiencies of the hydraulic machine depend to a considerable measure upon the length of the rotor vanes since just this length determines the length of contact surface between the rotor and casing in case of rotor pressing and the length of the sealing clearances through which the working fluid passes. As a result, the unilateral pressing of the rotor against the casing reduces the range of rotation frequencies (practically precluding operation at low frequencies) and decreases the service life and reliability of the machine.
Known in the art is another roller-vane hydraulic machine (SU, A, 992821) comprising a hollow casing with working fluid inlet and outlet passages and with hollows which open into the casing space. The hollows accommodate rollers directly interacting with the rotor accommodated inside the casing. The rotor is provided with vanes and, in combination with the casing, forms a working space divided by rollers into larger and smaller inter-roller chambers intercommunicated in pairs through the hydraulic relief radial passages made in the rotor. The rollers have slots for the passage of the rotor vanes, said rotor being installed with a provision for rotating in synchronism with the rollers under the effect of the supplied energy. The surfaces of the rollers form sealing clearances with the surface of the rotor. At the moment when the rollers pass the holes in the radial hydraulic relief passages in the rotor, the sealing clearances formed by the surfaces of the rollers and rotor become radically larger. This brings about a sharp growth of working fluid leaks which may result in stoppages of the rotor or, at the best, in its jerky motion. Operation at low speed in this case becomes impossible due to leaks of the working fluid.